This invention relates to wireless local area networks, such as those following the protocols of IEEE Standard 802.11.
The present invention may be used in conjunction with networks arranged to use wireless switches and access ports, such as the networks described in copending application Ser. No. 09/528,697, filed Mar. 17, 2000, the specification of which is incorporated herein by reference. It should be understood that the term “access port” as used in this application is the commercial name for the device referred to as an “RF Port” in the referenced copending application and the term “wireless switch” as used in this application is the commercial name for the device referred to as “Cell Controller” in the referenced copending application. The wireless switches of the present invention may also correspond to the cell controllers described in co-pending provisional application Ser. No. 60/473,755, filed May 28, 2003, the specification of which is incorporated herein by reference.
The method of the present invention may also be practiced in systems using the Wireless Switch Protocol (“WISP”) which is described in the application filed on Apr. 28, 2004, entitled “Protocol for Communications Between Access Ports and Wireless Switches” and owned by the assignee, incorporated herein by reference.
In accordance with the 802.11 standard, a basic service set (“BSS”) is a term used to describe a collection of devices which may communicate over a wireless local area network (“WLAN”). The BSS may or may not include an access point or access port which can bridge the wireless network with a fixed wired network such as an Ethernet network, and the set of stations in a BSS is generally controlled by a single coordination function, which determines when a station in the BSS may transmit/receive data.
Also in accordance with the 802.11 standard, identifiers are used to distinguish between BSSs. A basic service set identifier (“BSSID”) is used to identify a particular BSS. 802.11 access points as known in the prior art are configured with a single BSSID. The BSSID is generally six octets long, and is generally the same as the MAC address of the radio module in the access point. A BSSID is generally included within all frames transmitted on the wireless network.
An extended service set identifier (“ESSID”) is used to identify an extended service set (“ESS”), which is a set of two or more BSSs interconnected by a distribution system. An ESS allows a mobile user to move between BSSs within a single ESS and yet still remain “connected” to the fixed network (and thus can access the same files, receive e-mails, etc.) In accordance with the 802.11 standard, a BSSID may preferably support between 4-16 ESSIDs, or even more in further embodiments.
Mobile units in current wireless local area networks suffer the deficiency of receiving and processing all broadcast and multicast messages on the channel to which they are currently tuned and containing the BSSID to which they are associated—many or all of which may not be intended for the particular mobile unit. In mobile applications, the receipt and processing of such messages can cause unnecessary power consumption which results in depletion of battery life, since mobile units must unnecessarily wake from a sleep mode or other reduced power state in order to process these broadcast messages. Furthermore, during peak network traffic periods, receipt and processing of additional broadcast/multicast messages by each mobile unit in a system may result in additional unnecessary load on mobile unit processors.
Furthermore, application Ser. No. 10/773,931, filed on Feb. 6, 2004, the specification of which is fully incorporated herein by reference, describes a system and method for a virtual local area network. In connection with the network described therein, each wireless virtual local area network (“VLAN”) may use a different security scheme (such as WEP, AES, WPA, KeyGuard, Kerberos, and others known to those of ordinary skill in the art). It should be understood that the term “basic service set identifier” as used in this application is the same as the “primary service set identification” of the referenced copending application and the term “extended service set identifier” as used in this application is the same as the “secondary service set identification” of the referenced copending application.
Accordingly, when communicating through a common access point or access port using a common BSSID for the access port and unique ESSID for each VLAN segment of the network, message communications may be encrypted. However, 802.11 data broadcasts may or may not be encrypted depending on the lowest common denominator of security that is used for all broadcast multicast traffic when sharing one BSS across many VLAN segments.
Accordingly, it is an object of the invention to provide an improved wireless local area network system and method.